Real-time Kalman Filter Recursive Modulation Method of Parametric Array Sonar Transmission Signal

Abstract

The invention discloses a real time Kalman filtering recursion modulation method of parametric array sonar emission signal. The method comprises the following steps: take the signal to be modulated as an incoming signal after time discretization sampling; get a recursive envelope squared value of the parametric array emission signal through the Kalman filter; execute square foot over the obtained envelope squared value of the parametric array emission signal to get the envelope value of the emission signal; and then modulate the envelope and a carrier wave to get the parametric array emission signal. In the invention, the single in transient broadband unknown wave can be modulated distortionlessly; the computational complexity is small; and the noise in the incoming signal can be inhibited.

Description

technical field [0001] The invention belongs to the field of modulation of parametric array sonar transmission signals, in particular to a real-time Kalman filter recursive modulation method for parametric array sonar transmission signals capable of real-time modulation. Background technique [0002] The working process of the parametric array: After the transmitted signal of the parametric array is transmitted by the parametric array system, due to the nonlinear effect of the water medium, the excitation signal will be self-demodulated into a secondary wave signal in the water, and the secondary wave signal is what we expect Acoustic signal, the process is a nonlinear process. It is the Berktay far-field solution to describe the mathematical relationship between the transmitted signal of the parametric array and the secondary wave signal. The Berktay far field solution is Among them, E(t) is the envelope of the transmitted signal of the parametric array. Due to the nonli...

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Problems solved by technology

[0003] The earliest transmission signal modulation method of the parametric array system (or called the audio frequency directional system) is to use the signal as an envelope and carrier to perform double-sided band amplitude modulation. This method is simple to implement, but the distortion is relatively serious for broadband signals.

The square root modulation method pre-extracts the signal, and then performs double-sided band amplitude modulation with the carrier. This method significantly reduces the distortion of the secondary wave. If the compensation filter is performed at 12dB / oct before the amplitude modulation, then This method satisfies the no-distortion condition, but for broadband signals (especially in the case of unknown signal parameters, such as speech signals, random coded signals emitted by communication sonar), a good 12dB / oct compensation filter is not easy to implement and the implementation process is not enough Flexible, its application is limited by the actual situation

Although single sideband modulation reduces the bandwidth limitation of the transducer compared with double sideband modulation, it has serious intermodulation distortion for wideband signals

The double-integral pre-square extraction method is strictly in line with the Berktay far-field solution without distortion condition, but when this method is applied in engineering practice, the integration result is often 'diverge'

Other modulation methods require iterative calculations. Although they can be close to distortion-free after processing, the large amount of calculation is not conducive to real-time implementation

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